Power conversion device, control method for same, and electric power steering control device

ABSTRACT

Provided is a power conversion device for suppressing a variation amount of a bus current to decrease a power loss in consideration of control of detecting the bus current during operation. In control by a power conversion part in accordance with a switching signal, a voltage vector is caused to bring a mode into a power running mode at a timing of detecting the bus current when an AC rotating machine is in a power running operation state, and the voltage vector is caused to bring the mode into a regeneration mode at a timing of detecting the bus current when the AC rotating machine is in a regeneration operation state, thereby decreasing the power loss due to the variation in the bus current.

TECHNICAL FIELD

The present invention relates to a power conversion device, and thelike, and more particularly, to detection of a bus current duringoperation.

BACKGROUND ART

In a vehicle steering device disclosed in Patent Literature 1, the phaseof a sawtooth wave for generating a pulse width modulation (PWM) signalfor each phase is shifted to shift a timing of falling to the low levelof each of the PWM signals, thereby acquiring the value of a U phasecurrent flowing through an electric motor based on an output signal of acurrent sensor in a period from the fall to the low level of a V phasePWM signal to an elapse of a period T1. Moreover, a total current valueof the U phase current and a V phase current flowing through theelectric motor is acquired based on an output signal of a current sensorin a period from the fall to the low level of a W phase PWM signal to anelapse of a period T2.

CITATION LIST Patent Literature

[PTL 1] JP 2007-112416 A

SUMMARY OF INVENTION Technical Problem

With the vehicle steering device disclosed in Patent Literature 1, avoltage vector that is on in one phase or in two phases at the timing ofdetecting the bus current is realized by shifting the phase of thesawtooth wave for generating the phase pulse width modulation (PWM)signal for each phase. As a result, the current of each phase can bedetected based on the bus current. However, the carrier wave is shiftedto generate the PWM signals, and a sequence of the rise is thus fixed toa sequence set in advance. For example, the rise may be in a sequence ofthe minimum phase, an intermediate phase, and the maximum phasedepending on the angle of the motor, and a state (hereinafter referredto as regeneration mode) where a current flows from the motor to thepower supply is thus brought about at the detection timing based on thebus current even while the motor is in the power running operationstate, resulting in a large power loss. Moreover, the rise may be in asequence of the maximum phase, the intermediate phase, and the minimumphase, and a state (hereinafter referred to as power running mode) wherea current flows from the power supply to the motor is thus brought aboutat the detection timing based on the bus current even while the motor isin the regeneration operation state, resulting in a large power loss.

The present invention has been made in view of the above-mentionedproblem, and therefore has an object to provide a power conversiondevice, and the like, for suppressing a variation amount of a buscurrent to decrease a power loss in consideration of control ofdetecting the bus current during an operation.

Solution to Problem

According to one embodiment of the present invention, there are provideda power conversion device, and the like, including: an AC rotatingmachine including a multi-phase winding of three or more phases; a DCpower supply part configured to output a DC voltage; a voltage commandcalculation part configured to calculate a voltage command based on acontrol command from an outside for the AC rotating machine; a switchingsignal generation part configured to output a switching signalcorresponding to at least two voltage vectors corresponding to thevoltage command; a power conversion part configured to convert the DCvoltage from the DC power supply part to an AC voltage based on theswitching signal to supply the AC voltage to the AC rotating machine; acurrent detection part configured to detect a bus current, which is acurrent flowing between the DC power supply part and the powerconversion part; and a phase current calculation part configured tocalculate, based on the bus current, a phase current flowing through themulti-phase winding of the AC rotating machine, in which: the currentdetection part is configured to detect the bus current at timings atwhich the two voltage vectors are respectively output in accordance withthe switching signal; and the switching signal generation part isconfigured to output a switching signal corresponding to a voltagevector for supplying a current from the DC power supply part to the ACrotating machine at a timing at which the bus current is detected by thecurrent detection part when the AC rotating machine is in a powerrunning operation state.

Advantageous Effects of Invention

According to the present invention, it is possible to provide the powerconversion device, and the like, for suppressing the variation amount ofthe bus current to decrease the power loss in consideration of thecontrol of detecting the bus current during the operation.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram for illustrating an overall configuration of a powerconversion device according to a first embodiment of the presentinvention.

FIG. 2 is a table for showing an example of a relationship amongswitching signals, voltage vectors, and currents flowing through athree-phase winding in the power conversion device according to thefirst embodiment of the present invention.

FIG. 3 is a diagram for illustrating a relationship between the voltagevectors and phase directions of the three-phase winding of an ACrotating machine according to the present invention.

FIG. 4 is a diagram for illustrating an example of a basic structure ofa rotor of the AC rotating machine of FIG. 1.

FIG. 5 is an operation explanatory diagram for illustrating an exampleof switching signals in a switching signal generation part, detectiontimings for a bus current in a current detection part, and the voltagevectors in the power conversion device according to the first embodimentof the present invention.

FIG. 6 is an operation explanatory diagram for illustrating anotherexample of the switching signals in the switching signal generationpart, the detection timings for the bus current in the current detectionpart, and the voltage vectors in the power conversion device accordingto the first embodiment of the present invention.

FIG. 7 is an operation explanatory diagram for illustrating anotherexample of the switching signals in the switching signal generationpart, the detection timings for the bus current in the current detectionpart, and the voltage vectors in the power conversion device accordingto the first embodiment of the present invention.

FIG. 8 is an operation explanatory diagram for illustrating anotherexample of the switching signals in the switching signal generationpart, the detection timings for the bus current in the current detectionpart, and the voltage vectors in the power conversion device accordingto the first embodiment of the present invention.

FIG. 9 is an operation explanatory diagram for illustrating anotherexample of the switching signals in the switching signal generationpart, the detection timings for the bus current in the current detectionpart, and the voltage vectors in the power conversion device accordingto the first embodiment of the present invention.

FIG. 10 is an operation explanatory diagram for illustrating anotherexample of the switching signals in the switching signal generationpart, the detection timings for the bus current in the current detectionpart, and the voltage vectors in the power conversion device accordingto the first embodiment of the present invention.

FIG. 11 is an operation explanatory diagram for illustrating theswitching signals in the switching signal generation part, the detectiontimings for the bus current in the current detection part, and thevoltage vectors in a power conversion device according to a modifiedexample of the first embodiment of the present invention.

FIG. 12 is an operation explanatory diagram for illustrating an exampleof the switching signals in the switching signal generation part, thedetection timings for the bus current in the current detection part, thevoltage vectors, and the bus current in the power conversion deviceaccording to the first embodiment of the present invention.

FIG. 13 is an operation explanatory diagram for illustrating acomparative example of FIG. 12.

FIG. 14 is a diagram for illustrating a current vector on a plane havingd and q axis currents as axes in the power conversion device accordingto the first embodiment of the present invention.

FIG. 15 is a diagram for illustrating three-phase currents when a phaseangle θβ is 0 degrees in the power conversion device according to thefirst embodiment of the present invention.

FIG. 16 is a diagram for illustrating possible setting ranges of twovoltage vectors when the phase angle θβ is 0 degrees in the powerconversion device according to the first embodiment of the presentinvention.

FIG. 17 is a table for showing an example of possible setting ranges ofthe two voltage vectors and the voltage vectors when a combination ofthe two voltage vectors is switched at the minimum electrical angle forbringing the mode into the power running mode upon the current detectionfor the two voltage vectors in a power running operation state over onecycle of the electrical angle in the case where the phase angle θβ is 0degrees in the power conversion device according to the first embodimentof the present invention.

FIG. 18 is a table for showing an example of possible setting ranges ofthe two voltage vectors and the voltage vectors when the combination ofthe two voltage vectors is switched at the maximum electrical angle forbringing the mode into the power running mode upon the current detectionfor the two voltage vectors in the power running operation state overone cycle of the electrical angle in the case where the phase angle θβis 0 degrees in the power conversion device according to the firstembodiment of the present invention.

FIG. 19 is a diagram for illustrating three-phase currents when thephase angle θβ is 45 degrees in the power conversion device according tothe first embodiment of the present invention.

FIG. 20 is a diagram for illustrating possible setting ranges of the twovoltage vectors when the phase angle θβ is 45 degrees in the powerconversion device according to the first embodiment of the presentinvention.

FIG. 21 is a table for showing an example of possible setting ranges ofthe two voltage vectors and the voltage vectors when the combination ofthe two voltage vectors is switched at the minimum electrical angle forbringing the mode into the power running mode upon the current detectionfor the two voltage vectors in the power running operation state overone cycle of the electrical angle in the case where the phase angle θβis 45 degrees in the power conversion device according to the firstembodiment of the present invention.

FIG. 22 is a table for showing an example of possible setting ranges ofthe two voltage vectors and the voltage vectors when the combination ofthe two voltage vectors is switched at the maximum electrical angle forbringing the mode into the power running mode upon the current detectionfor the two voltage vectors in the power running operation state overone cycle of the electrical angle in the case where the phase angle θβis 45 degrees in the power conversion device according to the firstembodiment of the present invention.

FIG. 23 is a table for showing an example of selection of the twovoltage vectors when the combination of the two voltage vectors isswitched at the minimum electrical angle for bringing the mode into thepower running mode upon the current detection for the two voltagevectors in the power running operation state at any phase angle θβ ofbetween 0 degrees and 45 degrees in the power conversion deviceaccording to the first embodiment of the present invention.

FIG. 24 is a table for showing an example of selection of the twovoltage vectors when the combination of the two voltage vectors isswitched at the maximum electrical angle for bringing the mode into thepower running mode upon the current detection for the two voltagevectors in the power running operation state at any phase angle θβ ofbetween 0 degrees and 45 degrees in the power conversion deviceaccording to the first embodiment of the present invention.

FIG. 25 is a diagram for illustrating the three phase currents when thephase angle θβ is 180 degrees in the power conversion device accordingto the first embodiment of the present invention.

FIG. 26 is a diagram for illustrating the three phase currents when thephase angle θβ is 135 degrees in the power conversion device accordingto the first embodiment of the present invention.

FIG. 27 is a table for showing an example of possible setting ranges ofthe two voltage vectors and the voltage vectors when the combination ofthe two voltage vectors is switched at the minimum electrical angle forbringing the mode into the power running mode upon the current detectionfor the two voltage vectors in the power running operation state overone cycle of the electrical angle in the case where the phase angle θβis 180 degrees in the power conversion device according to the firstembodiment of the present invention.

FIG. 28 is a table for showing an example of possible setting ranges ofthe two voltage vectors and the voltage vectors when the combination ofthe two voltage vectors is switched at the maximum electrical angle forbringing the mode into the power running mode upon the current detectionfor the two voltage vectors in the power running operation state overone cycle of the electrical angle in the case where the phase angle θβis 180 degrees in the power conversion device according to the firstembodiment of the present invention.

FIG. 29 is a table for showing an example of possible setting ranges ofthe two voltage vectors and the voltage vectors when the combination ofthe two voltage vectors is switched at the minimum electrical angle forbringing the mode into the power running mode upon the current detectionfor the two voltage vectors in the power running operation state overone cycle of the electrical angle in the case where the phase angle θβis 135 degrees in the power conversion device according to the firstembodiment of the present invention.

FIG. 30 is a table for showing an example of possible setting ranges ofthe two voltage vectors and the voltage vectors when the combination ofthe two voltage vectors is switched at the maximum electrical angle forbringing the mode into the power running mode upon the current detectionfor the two voltage vectors in the power running operation state overone cycle of the electrical angle in the case where the phase angle θβis 135 degrees in the power conversion device according to the firstembodiment of the present invention.

FIG. 31 is a table for showing an example of setting ranges of the twovoltage vectors and the voltage vectors when the combination of the twovoltage vectors is switched at the minimum electrical angle for bringingthe mode into the power running mode upon the current detection for thetwo voltage vectors in the power running operation state at any phaseangle θβ of between 135 degrees and 180 degrees in the power conversiondevice according to the first embodiment of the present invention.

FIG. 32 is a table for showing an example of setting ranges of the twovoltage vectors and the voltage vectors when the combination of the twovoltage vectors is switched at the maximum electrical angle for bringingthe mode into the power running mode upon the current detection for thetwo voltage vectors in the power running operation state at any phaseangle θβ of between 135 degrees and 180 degrees in the power conversiondevice according to the first embodiment of the present invention.

FIG. 33 is a diagram for illustrating possible setting ranges of thevoltage vectors for outputting the two voltage vectors for bringing themode into the power running mode in the power running operation statefor an arbitrary phase angle θβ in the power conversion device accordingto a second embodiment of the present invention.

FIG. 34 is a table for showing an example of the setting ranges of thetwo voltage vectors and the voltage vectors when the combination of thetwo voltage vectors for bringing the mode into the power running mode inthe power running operation state is switched at the minimum electricalangle for an arbitrary phase angle θβ in the power conversion deviceaccording to the second embodiment of the present invention.

FIG. 35 is a table for showing an example of the setting ranges of thetwo voltage vectors and the voltage vectors when the combination of thetwo voltage vectors for bringing the mode into the power running mode inthe power running operation state is switched at the minimum electricalangle for an arbitrary phase angle θβ in the power conversion deviceaccording to the second embodiment of the present invention.

FIG. 36 is a diagram for illustrating an overall configuration of apower conversion device according to a third embodiment of the presentinvention.

FIG. 37 is an operation explanatory diagram for illustrating an exampleof the switching signals in the switching signal generation part, thedetection timings for the bus current in the current detection part, thevoltage vectors, and the bus current in the power conversion deviceaccording to the third embodiment of the present invention.

FIG. 38 is an operation explanatory diagram for illustrating acomparative example of FIG. 37.

FIG. 39 is a diagram for illustrating an example of a configuration of acontrol device for an electric power steering for which the powerconversion device according to the present invention is provided.

DESCRIPTION OF EMBODIMENTS

In a power conversion device, and the like, according to the presentinvention, a power loss due to a variation in a bus current can bedecreased by causing voltage vectors to bring a mode into a powerrunning mode upon a timing of detection of the bus current when an ACrotating machine is in a power running operation state in control of apower conversion part by using switching signals in consideration ofcontrol of detecting the bus current during operation. Moreover, thepower loss due to the variation in the bus current can be decreased bycausing the voltage vectors to bring the mode into a regeneration modeat the timing of the detection of the bus current when the AC rotatingmachine is in a regeneration operation state.

A description is now given of respective embodiments of the powerconversion device, and the like, according to the present inventionreferring to the drawings. In the respective embodiments, the same orcorresponding components are denoted by the same numerals, and aredundant description thereof is not given.

First Embodiment

FIG. 1 is a diagram for illustrating an overall configuration of a powerconversion device according to a first embodiment of the presentinvention. An AC rotating machine 1 is constructed by a permanent magnetsynchronous rotating machine including a three-phase winding (generally,multi-phase winding) C having three phases U, V, and W.

A DC power supply 2 is configured to output a DC voltage Vdc to a powerconversion part 3. This DC power supply 2 may include all devices thatare configured to output a DC voltage, e.g., a battery, a DC-DCconverter, a diode rectifier, and a PWM rectifier (any of which is notshown).

The power conversion part 3 is configured to turn on/off semiconductorswitches Sup to Swn in accordance with switching signals Qup to Qwn,thereby applying power conversion to the DC voltage Vdc input from theDC power supply 2, and applying AC voltages on the three-phase windingsU, V and W of the AC rotating machine 1. As each of the semiconductorswitches Sup to Swn, a semiconductor switching device, e.g., an IGBT, abipolar transistor, or a MOS power transistor and a diode connected toeach other in an anti-parallel connection state are used. On thisoccasion, the switching signals Qup, Qun, Qvp, Qvn, Qwp, and Qwn areswitching signals for respectively turning on/off the semiconductorswitches Sup, Sun, Svp, Svn, Swp, and Swn in the power conversion part3.

A smoothing capacitor 4 is configured to suppress a variation in thecurrent flowing through a bus (BU), thereby realizing a stable DCcurrent. In addition to a true capacitor capacitance Cc, an equivalentserial resistance Rc and a lead inductance Lc exist, which are notillustrated in detail. When charge is sufficiently accumulated, acurrent is generally supplied not from the DC power supply 2, but fromthe smoothing capacitor 4 to the AC rotating machine 1, and adescription is given while the smoothing capacitor 4 is included in theconfiguration. However, an internal resistance exists in the DC powersupply 2, and the same description is thus given of a case without thesmoothing capacitor 4.

The DC power supply 2 or the part formed by the DC power supply 2 andthe smoothing capacitor 4 constructs a DC power supply part.

A switching signal generation part 5 is configured to output theswitching signals Qup to Qwn to which the pulse width modulation (PWMmodulation) is applied in accordance with voltage commands Vu, Vv, andVw output from a voltage command calculation part 6. The switchingsignals Qup to Qwn have pulse widths in accordance with the voltagecommands Vu, Vv, and Vw.

On this occasion, according to the first embodiment, the powerconversion part 3 is assumed to carry out an operation of converting theDC voltage from the DC power supply 2 or the smoothing capacitor to theAC voltage in accordance with the switching signals Qup to Qwn, andsupplying the AC voltages to the AC rotating machine 1 in the powerrunning operation. Moreover, according to a third embodiment of thepresent invention described later, the power conversion part 3 isassumed to carry out an operation of converting an electromotive forceof the AC rotating machine 1 to the DC voltage in accordance with theswitching signals Qup to Qwn, and supplying the DC voltage to the DCpower supply or the smoothing capacitor in the regeneration operation.

Moreover, a case in which the power conversion part 3 carries out bothof the operation in the power running state and the operation in theregeneration state is included as described later according to thepresent invention.

According to the present invention, the switching signals Qup to Qwn areoutput to the power conversion part 3 as well as the current detectionpart 7 and the phase current calculation part 8 for the currentdetection, and the current detection part 7 and the phase currentcalculation part 8 are configured to respectively carry out thedetection and the calculation in accordance with the switching signalsQup to Qwn. All the switching signals Qup to Qwn do not need to beoutput to the current detection part 7 and the phase current calculationpart 8, and the same effect can be provided by using, for example, upperswitching signals Qup, Qvp and Qwp or using another state variable thatcan represent states of the switching signals Qup to Qwn.

The voltage command calculation part 6 is configured to calculate thevoltage commands Vu, Vv, and Vw for driving the AC rotating machine 1,and output the voltage commands Vu, Vv, and Vw to the switching signalgeneration part 5. As a calculation method for the voltage commands Vu,Vv, and Vw, for example, there is given V/F control of setting a speed(frequency) command f for the AC rotating machine 1 as the controlcommand of FIG. 1 to determine the amplitude of the voltage commands.Moreover, there is used current feedback control of setting a currentcommand for the AC rotating machine 1 as the control command, andcalculating the voltage commands Vu, Vv, and Vw so that, based ondeviations between the set control command (=current command) and thecurrents (phase currents) Iu, Iv, and Iw output by the phase currentcalculation part 8 described later and flowing through the three-phasewinding, the deviations are zero by means of the proportional-integralcontrol or the like.

The V/F control is feedforward control, and does not require thethree-phase currents Iu, Iv, and Iw. Thus, the input of the three-phasecurrents Iu, Iv, and Iw to the voltage command calculation part 6 is notessential in this case.

The current detection part 7 is configured to detect a bus current Idc,which is a current flowing between the DC power supply 2 and the powerconversion part 3, and output a detection result to the phase currentcalculation part 8. The current detection part 7 is constructed by ashunt resistor 7 a and a sample-and-hold device 7 b configured to sampleand hold the current flowing through the shunt resistor 7 a, therebydetecting the bus current Idc. A current transformer (CT) may be used inplace of the shunt resistor 7 a, and in this case, an output voltage ofthe current transformer is sampled and held by the sample-and-holddevice 7 b, thereby detecting the bus current Idc.

A description is now given of a relationship between voltage vectorsbased on the switching signals Qup to Qwn, the bus current Idc, and thecurrents Iu, Iv, and Iw flowing through the three-phase winding. In FIG.2, the relationship among the switching signals Qup to Qwn, the voltagevectors, and the currents Iu, Iv, and Iw flowing through the three-phasewinding is illustrated. In FIG. 2, when the value of one of Qup to Qwnis 1, one of the semiconductor switches Sup to Swn corresponding to theone of Qup to Qwn having the value of 1 is on. When the value of one ofQup to Qwn is 0, one of the semiconductor switches Sup to Swncorresponding to the one of Qup to Qwn having the value of 0 is off.

The voltage vectors are illustrated in FIGS. 3. V1 to V6 are vectorsdifferent in the phase by 60 degrees from each other. V1, V3, and V5have U, V, W phase directions of the three-phase winding, respectively.Moreover, V0 and V7 are voltage vectors having the magnitude of zero.

The phase current calculation part 8 is configured to output Iu, Iv, andIw from the relationship shown in FIG. 2 based on the bus current Idcand the switching signals Qup to Qwn. V0 and V7 cannot be used to detectthe three-phase currents based on the bus current. Thus, for example,the voltage vector V1 is output to detect Iu, and the voltage vector V2is output to detect −Iw. There may be provided such a configurationthat, based on the fact that, in the three-phase three-line rotatingmachine, a sum of the currents flowing through the three phases is zero,the acquired detected current values for the two phases are used tocalculate a current of the remaining one phase. In other words, onlysuch a configuration that appropriate voltage vectors are selected todetect the currents for at least two phases is necessary.

A position detector 100 is configured to output a phase 8 of the ACrotating machine 1 to the switching signal generation part 5.

A detailed description is now given of the AC rotating machine 1. FIG. 4is a diagram for illustrating a basic structure of a rotor of the ACrotating machine 1, and showing such a structure that permanent magnets41 to 44 are embedded inside an iron core. Flux barriers are provided onboth ends of each of the permanent magnets 41 to 44. In FIG. 4, adirection of a field pole generated by the permanent magnets is set tothe d axis, and a direction advanced by 90 degrees in the electricalangle is set to the q axis. A case of a four-pole machine is illustratedin FIG. 4, and a direction advanced in 45 degrees in the mechanicalangle with respect to the d axis is the q axis. The rotating machine 1having this rotor structure is referred to as interior magnetsynchronous rotating machine, has saliency, and there is a relationshipLd<Lq between a d axis inductance Ld and a q axis inductance Lq.

A description has been given of the interior magnet synchronous rotatingmachine where Ld≠Lq is satisfied, but Ld=Lq may be satisfied accordingto the present invention, which applies to all the AC rotating machines.For example, the present invention can be applied to other AC rotatingmachines, e.g., a surface magnet synchronous rotating machine, an insetpermanent magnet synchronous rotating machine, a synchronous reluctancemotor, and a switched reluctance motor. Moreover, a description is givenof the rotor having four poles in FIG. 4, but the present invention canbe applied to an AC rotating machine having an arbitrary number of polesas long as the number of the poles is an even natural number (notincluding 0).

A detailed description is now given of the switching signal generationpart 5. FIG. 5 is an operation explanatory diagram relating to a methodof generating the switching signals Qup to Qwn in the switching signalgeneration part 5, and the detection timings of the bus current Idc inthe current detection part 7 in a cycle Ts of the switching signalsaccording to the first embodiment. Qun, Qvn, and Qwn illustrated in FIG.2 are respectively in an inverted relationship (0 for 1 and 1 for 0except for a dead time period) with Qup, Qvp, and Qwp, and are thus notillustrated.

Qup is set to 1, and Qvp and Qwp are set to 0 at a time point t1(n), andthis switching pattern is maintained until a time point t2(n) after anelapse of Δt1 from the time point t1(n). With reference to FIG. 2, thevoltage vector is V1 from the time point t1(n) to the time point t2(n).A first bus current Idc is detected at a time point ts1-1(n) in theperiod from the time point t1(n) to the time point t2(n). Δt1 is a setto a period longer than a sum of a dead time of the power conversionpart 3 and a period for the current detection part 7 to detect the buscurrent Idc (such as a period required for settlement of ringingincluded in a detected waveform and a period required for the samplingand holding). With reference to FIG. 2, the voltage vector is V1 fromthe time point t1(n) to the time point t2(n), and the bus current Idcdetected at the time point ts1-1(n) is equal to the current Iu flowingthrough the U phase.

Then, Qvp is set to 1 at the time point t2(n), and this switchingpattern is maintained until a time point t3(n). With reference to FIG.2, the voltage vector is V2 from the time point t2(n) to a time pointt3(n). The bus current Idc is again detected at a time point ts1-2(n) atthis timing. Δt2 is determined in the same way as in the case of Δt1. Ingeneral, Δt1=Δt2 is set. With reference to FIG. 2, the bus current Idcdetected at the time point ts1-2(n) is equal to a value −Iw acquired byinverting the sign of the current flowing through the W phase. Then, Qwpis set to 1 at the time point t3(n). Pulse widths (periods in which thevalue 1 is maintained) of Qup to Qwp are determined by the voltagecommands Vu, Vv, and Vw, and timings at which Qup to Qwp become 0 arethus determined in accordance with the pulse widths.

In the example illustrated in FIG. 5, the two voltage vectors V1 and V2are generated by setting Qup, Qvp, and Qwp to 1 in this sequence, andthe bus current Idc is detected during the generations of those voltagevectors in this way. On this occasion, the following five cases otherthan the example of FIG. 5 are conceivable by switching the sequence ofsetting the switching signals Qup to Qwp to 1.

In a first case, as illustrated in FIG. 6, the two voltage vectors V3and V2 are generated by setting Qvp, Qup, and Qwp to 1 in this sequence,and the bus current Idc is detected during the generations of thosevoltage vectors. With reference to FIG. 2, the bus current Idc detectedat the time point ts1-1(n) is equal to the current Iv flowing throughthe V phase, and the bus current Idc detected at the time point ts1-2(n)is equal to a sign-inverted value −Iw of the current flowing through theW phase.

In a second case, as illustrated in FIG. 7, the two voltage vectors V3and V4 are generated by setting Qvp, Qwp, and Qup to 1 in this sequence,and the bus current Idc is detected during the generations of thosevoltage vectors. With reference to FIG. 2, the bus current Idc detectedat the time point ts1-1(n) is equal to the current Iv flowing throughthe V phase, and the bus current Idc detected at the time point ts1-2(n)is equal to a sign-inverted value −Iu of the current flowing through theU phase.

In a third case, as illustrated in FIG. 8, the two voltage vectors V5and V4 are generated by setting Qwp, Qvp, and Qup to 1 in this sequence,and the bus current Idc is detected during the generations of thosevoltage vectors. With reference to FIG. 2, the bus current Idc detectedat the time point ts1-1(n) is equal to the current Iw flowing throughthe W phase, and the bus current Idc detected at the time point ts1-2(n)is equal to the sign-inverted value −Iu of the current flowing throughthe U phase.

In a fourth case, as illustrated in FIG. 9, the two voltage vectors V5and V6 are generated by setting Qwp, Qup, and Qvp to 1 in this sequence,and the bus current Idc is detected during the generations of thosevoltage vectors. With reference to FIG. 2, the bus current Idc detectedat the time point ts1-1(n) is equal to the current Iw flowing throughthe W phase, and the bus current Idc detected at the time point ts1-2(n)is equal to a sign-inverted value −Iv of the current flowing through theV phase.

In a fifth case, as illustrated in FIG. 10, the two voltage vectors V1and V6 are generated by setting Qup, Qwp, and Qvp to 1 in this sequence,and the bus current Idc is detected during the generations of thosevoltage vectors. With reference to FIG. 2, the bus current Idc detectedat the time point ts1-1(n) is equal to the current Iu flowing throughthe U phase, and the bus current Idc detected at the time point ts1-2(n)is equal to a sign-inverted value −Iv of the current flowing through theV phase.

According to the first embodiment, the combinations (“V1, V2”, “V3, V2”,“V3, V4”, “V5, V4”, “V5, V6”, and “V1, V6”) of the two voltage vectorsin the six patterns illustrated in FIG. 5 to FIG. 10 upon the buscurrent detections are switched to be output in accordance with therotational position 8 of the AC rotating machine 1.

According to the first embodiment, a description is given of the methodof shifting the timing of raising the PWM pulse in the six patternsillustrated in FIG. 5 to FIG. 10, thereby generating the desired voltagevector and detecting the bus current Idc, but a timing of dropping thePWM pulse may be sifted, thereby generating the desired voltage vectorand detecting the bus current Idc as illustrated in FIG. 11. Asillustrated in FIG. 11, the two voltage vectors V4 and V5 are generatedby setting Qup, Qvp, and Qwp to 0 in this sequence, and the bus currentIdc is detected during the generations of the voltage vectors. Withreference to FIG. 2, the bus current Idc detected at the time pointts1-1(n) is equal to a sign-inverted value −Iu of the current flowingthrough the U phase, and the bus current Idc detected at the time pointts1-2(n) is equal to the Iw flowing through the W phase.

As the cases illustrated in FIG. 6 to FIG. 10, the following five casesother than the example of FIG. 11 are conceivable by switching thesequence of setting the switching signals Qup to Qwp to 0. Also in thiscase, the combinations (“V1, V2”, “V3, V2”, “V3, V4”, “V5, V4”, “V5,V6”, and “V1, V6”) of the two voltage vectors in the six patterns uponthe bus current detections exit, and the same effect is provided as inthe cases illustrated in FIG. 5 to FIG. 10.

A description is now given of a difference in the bus current inaccordance with the combination of the two voltage vectors for a casewhere Iu>Iv>0 and Iw<0 are satisfied while the AC rotating machine 1 isin the power running operation state.

FIG. 12 is a diagram for illustrating an operation when the two voltagevectors V1 and V2 are generated by setting Qup, Qvp, and Qwp to 1 inthis sequence, and the bus current Idc is detected during thegenerations of the voltage vectors. The sum of the three-phase currentsis zero, and when any one of the three-phase currents has a differentvalue, the current in least one phase thus has a negative value.

The bus current Idc detected at the time point ts1-1(n) is equal to thecurrent Iu flowing through the U phase, the bus current Idc has apositive value, and the mode is in the power running mode in which thebus current Idc flows from the DC power supply 2 or the smoothingcapacitor 4 to the AC rotating machine 1.

The bus current Idc detected at the time point ts1-2(n) is equal to thesign-inverted value −Iw flowing through the W phase, the bus current Idchas a positive value, and the mode is in the power running mode in whichthe bus current Idc flows from the DC power supply 2 or the smoothingcapacitor 4 to the AC rotating machine 1.

FIG. 13 is a diagram for illustrating an operation when the two voltagevectors V5 and V4 are generated by setting Qwp, Qvp, and Qup to 1 inthis sequence, and the bus current Idc is detected during thegenerations of the voltage vectors.

The bus current Idc detected at the time point ts1-1(n) is equal to thecurrent Iw flowing through the W phase, the bus current Idc has anegative value, and the mode is in the regeneration mode in which thebus current Idc flows from the AC rotating machine 1 to the DC powersupply 2 or the smoothing capacitor 4.

The bus current Idc detected at the time point ts1-2(n) is equal to thesign-inverted value −Iu flowing through the U phase, the bus current Idchas a negative value, and the mode is in the regeneration mode in whichthe bus current Idc flows from the AC rotating machine 1 to the DC powersupply 2 or the smoothing capacitor 4.

A power loss in the smoothing capacitor 4 is acquired by a product ofthe square of the bus current Idc and the equivalent serial resistanceRc. When the voltage vectors are selected as illustrated in FIG. 12, apower loss is generated in portions in the power running mode other thanregions in which the voltage vector is V0 or V7. When the voltagevectors are selected as illustrated in FIG. 13, the period of the powerrunning mode is increased by a period of the regeneration mode, a powerloss is generated even in the regeneration mode, and a power lossincreases when the voltage vectors, which bring the mode into theregeneration mode in the power running operation state, are selected.

Thus, the switching signal generation part 5 is configured to output theswitching signals corresponding to the two voltage vectors that bringthe mode into the power running mode upon the current detection in thepower running operation state in order to decrease the power loss in thefirst embodiment.

A description is now given of a method of selecting the two voltagevectors that bring the mode into the power running mode in the powerrunning operation state.

As illustrated in FIG. 14, when the phase angle θβ of a current vectoris defined on a plane having the d and q axis currents as axes, and acurrent effective value is denoted by Irms, the three-phase currents arerepresented as Equation (1).

iu1=√(2)·Irms·sin(θ+θβ−π)

iv1=√(2)·Irms·sin(θ+θβ+(π/3))

iw1=√(2)·Irms·sin(θ+θβ−(π/3))   (1)

Moreover, the torque acquired on the AC rotating machine 1 isrepresented as Equation (2). When the reluctance torque does not exist,the output torque is determined in accordance with the magnitude of theq axis current iq independently of the d axis current id. When thereluctance torque exists, the output torque varies in accordance with adistribution between id and iq, and the phase angle θβ of the currentvector that provides the maximum torque at the minimum current is in arange of from 0 degrees to 45 degrees or from 135 degrees to 180degrees.

T=Pm·{φ+(Ld−Lq )id}iq   (2)

where:

T: torque,

Pm: number of pairs of poles,

φ: magnetic flux,

Ld: d axis inductance,

Lq: q axis inductance,

id: d axis current, and

iq: q axis current.

The three-phase currents when the phase angle θβ is 0 degrees areillustrated in FIG. 15. The U phase current Iu is equal to or more than0 in a range of from 180 degrees to 360 degrees. The V phase current Ivis equal to or more than 0 in a range of from 0 degrees to 120 degreesand in a range of from 300 degrees to 360 degrees. The W phase currentIw is equal to or more than 0 in a range of from 60 degrees to 240degrees.

In other words, in order to bring the mode into the power running modeupon the current detection for the first voltage vector, when thevoltage vector is the voltage vector V1, the range needs to be from 180degrees to 360 degrees,

when the voltage vector is the voltage vector V3, the range needs to befrom 0 degrees to 120 degrees or from 300 degrees to 360 degrees, and

when the voltage vector is the voltage vector V5, the range needs to befrom 60 degrees to 240 degrees.

On the other hand, the U phase current Iu is equal to or less than 0 ina range of from 0 degrees to 180 degrees. The V phase current Iv isequal to or less than 0 in a range of from 120 degrees to 300 degrees.The W phase current Iw is equal to or less than 0 in a range of from 0degrees to 60 degrees and in a range of from 240 degrees to 360 degrees.

In other words, in order to bring the mode into the power running modeupon the current detection for the second voltage vector,

when the voltage vector is the voltage vector V4, the range needs to befrom 0 degrees to 180 degrees,

when the voltage vector is the voltage vector V6, the range needs to befrom 120 degrees to 300 degrees, and

when the voltage vector is the voltage vector V2, the range needs to befrom 0 degrees to 60 degrees or from 240 degrees to 360 degrees.

Possible setting ranges of the two voltage vectors are illustrated inFIG. 16. For example, for a case where the electrical angle is 90degrees, the switching signals need to be set to 1 in any one of asequence of Qvp, Qwp, and Qup (V3, V4) and a sequence of Qwp, Qvp, andQup (V5, V4). In other words, two options exist for the first voltagevector in the ranges of from 60 degrees to 120 degrees, from 180 degreesto 240 degrees, and from 300 degrees to 360 degrees. Moreover, twooptions exist for the second voltage vector in the ranges of from 0degrees to 60 degrees, from 120 degrees to 180 degrees, and from 240degrees to 300 degrees.

Examples in which the mode becomes the power running mode upon thecurrent detection for the two voltage vectors in the power runningoperation state over one cycle of the electrical angle are shown in FIG.17 and FIG. 18.

FIG. 17 is a table for showing a case where the switching of thecombination of the two voltage vectors is carried out at the minimumelectrical angle in each of the possible setting ranges extending over180 degrees.

FIG. 18 is a table for showing a case where the switching of thecombination of the two voltage vectors is carried out at the maximumelectrical angle in each of the possible setting ranges extending over180 degrees.

The same effect as that of those two cases can be acquired by selectingthe two voltage vectors included in the possible setting ranges of FIG.16.

The three-phase currents when the phase angle θβ is 45 degrees areillustrated in FIG. 19. The U phase current Iu is equal to or more than0 in a range of from 135 degrees to 315 degrees. The V phase current Ivis equal to or more than 0 in a range of from 0 degrees to 75 degreesand in a range of from 255 degrees to 360 degrees. The W phase currentIw is equal to or more than 0 in a range of from 15 degrees to 195degrees.

In other words, in order to bring the mode into the power running modeupon the current detection for the first voltage vector, when thevoltage vector is the voltage vector V1, the range needs to be from 135degrees to 315 degrees,

when the voltage vector is the voltage vector V3, the range needs to befrom 0 degrees to 75 degrees or from 255 degrees to 360 degrees, and

when the voltage vector is the voltage vector V5, the range needs to befrom 15 degrees to 195 degrees.

On the other hand, the U phase current Iu is equal to or less than 0 ina range of from 0 degrees to 135 degrees and 315 degrees to 360 degrees.The V phase current Iv is equal to or less than 0 in a range of from 75degrees to 255 degrees. The W phase current Iw is equal to or less than0 in a range of from 0 degrees to 15 degrees and in a range of from 195degrees to 360 degrees.

In other words, in order to bring the mode into the power running modeupon the current detection for the second voltage vector,

when the voltage vector is the voltage vector V4, the range needs to befrom 0 degrees to 135 degrees and 315 degrees to 360 degrees,

when the voltage vector is the voltage vector V6, the range needs to befrom 75 degrees to 255 degrees, and

when the voltage vector is the voltage vector V2, the range needs to befrom 0 degrees to 15 degrees or from 195 degrees to 360 degrees.

Possible setting ranges of the two voltage vectors are illustrated inFIG. 20. For easy comparison with FIG. 16, only the axis of theelectrical angle is shifted. For example, for the case where theelectrical angle is 45 degrees, the switching signals need to be set to1 in any one of a sequence of Qvp, Qwp, and Qup and a sequence of Qwp,Qvp, and Qup.

Examples in which the mode is the power running mode upon the currentdetection for the two voltage vectors in the power running operationstate over one cycle of the electrical angle are shown in FIG. 21 andFIG. 22 in the same manner as the case where the phase angle θβ is 0degrees.

FIG. 21 is a table for showing a case where the switching of thecombination of the two voltage vectors is carried out at the minimumelectrical angle in each of the possible setting ranges extending over180 degrees.

FIG. 22 is a table for showing a case where the switching of thecombination of the two voltage vectors is carried out at the maximumelectrical angle in each of the possible setting ranges extending over180 degrees.

The same effect as that of those two cases can be acquired by selectingthe two voltage vectors included in the possible setting ranges of FIG.20.

With reference to FIG. 17, FIG. 18, FIG. 21, and FIG. 22, in order tobring the mode into the power running mode upon the current detectionfor the two voltage vectors in the power running operation state at anyphase angle θβ between 0 degrees and 45 degrees, the two voltage vectorsonly need to be selected, for example, as in FIG. 23 or FIG. 24.

Moreover, the same effect as that of those two cases can be acquired byselecting the two voltage vectors satisfying the possible setting rangesof FIG. 16 and FIG. 20.

The three-phase currents in a case where the phase angle θβ is 180degrees are illustrated in FIG. 25, and the three-phase currents in acase where the phase angle θβ is 135 degrees are illustrated in FIG. 26.

Examples in which the mode becomes the power running mode upon thecurrent detection for the two voltage vectors in the power runningoperation state over one cycle of the electrical angle are shown in FIG.27 and FIG. 28 in the case where the phase angle θβ is 180 degrees. FIG.27 is a table for showing a case where the combination of the twovoltage vectors is switched at the minimum electrical angle. FIG. 28 isa table for showing a case where the combination of the two voltagevectors is switched at the maximum electrical angle. The same effect asthat of those two cases can be acquired by selecting the two voltagevectors included in the possible setting ranges, which are notillustrated.

Examples in which the mode becomes the power running mode upon thecurrent detection for the two voltage vectors in the power runningoperation state over one cycle of the electrical angle are shown in FIG.29 and FIG. 30 in the case where the phase angle θβ is 135 degrees. FIG.29 is a table for showing a case where the combination of the twovoltage vectors is switched at the minimum electrical angle. FIG. 30 isa table for showing a case where the combination of the two voltagevectors is switched at the maximum electrical angle. The same effect asthat of those two cases can be acquired by selecting the two voltagevectors included in the possible setting ranges, which are notillustrated.

With reference to FIG. 27 to FIG. 30, in order to bring the mode intothe power running mode upon the current detection for the two voltagevectors in the power running operation state at any phase angle θβbetween 135 degrees and 180 degrees, the two voltage vectors only needto be selected, for example, as in FIG. 31 or FIG. 32.

Moreover, the same effect as that of those two cases can be acquired byselecting the two voltage vectors satisfying the possible setting rangesat any phase angle θβ.

For example, by selecting the two voltage vectors as in FIG. 23 for thecase where the q axis component of the current vector is positive, andas in FIG. 31 for the case where the q axis component of the currentvector is negative, the two voltage vectors for bringing the mode intothe power running mode in the power running operation state can beoutput, thereby detecting the current to decrease the power loss.

The current vector on this occasion is based on the detected current orthe current command when the current command is included in the controlcommand, but a voltage vector based on a voltage command can provide thesame effect. In other words, the switching signal generation part 5 canselect the voltage vectors based on at least one of the direction of oneof the axial direction components in the two-axis coordinate system ofthe current command when the control command includes the currentcommand, the direction of one of the axial direction components in thetwo-axis coordinate system of the voltage command, and the direction ofone of the axial direction components in the two-axis coordinate systemof the detected current (phase current) acquired by the phase currentcalculation part 8, thereby decreasing the power loss, which is aneffect that has not hitherto been provided.

The power running and the regeneration are switched therebetween whenthe voltage vector remains normal, but the detection can be carried outin the power running mode by the switching based on the positive andnegative of the q axis current.

According to this embodiment, the phase angle θβ to be considered is setto the range of from 0 degrees to 45 degrees or from 135 degrees to 180degrees, but even when the range of the phase angle θβ to be consideredis different, the two voltage vectors for bringing the mode into thepower running mode in the power running operation state can be output byusing the same method to select the two voltage vectors, therebydetecting the current to decrease the power loss.

When the amplitude Vmap of the voltage commands Vu, Vv, and Vw becomesmore than a threshold set in advance, the two voltage vectors for thedetection of the bus current may be selected based on the sequence inthe magnitude of the voltage command. The selection of the two voltagevectors based on the sequence in the magnitude of the voltage command isequivalent to selection of the two voltage vectors neighboring thevoltage command vector. Thus, the bus current is detected at a timing atwhich the voltage vectors neighbor the voltage command vector.

As a result, voltage vectors minimizing the power loss can be selectedin a low modulation factor region where the voltage vectors can freelybe selected, and necessary voltage vectors can be selected in a highmodulation factor region where selectable combinations of the voltagevectors are limited, thereby suppressing the power loss at the highmodulation factor.

Further, the power conversion device according to the present inventioncan be provided on an electric power steering so that the AC rotatingmachine 1 can generate a torque for assisting a steering torque of asteering system. As a result, there is provided such an effect that asteering system low in the power loss can be constructed. Moreover, atorque ripple can be suppressed on the electric power steering sensitiveto vibration.

An example of a configuration of a control device for the electric powersteering according to the present invention is schematically illustratedin FIG. 39. The AC rotating machine 1 is attached to a steering shaft soas to apply the assist torque, and a power conversion unit PT isconstructed by portions other than the AC rotating machine 1 of FIG. 1,and the like.

Second Embodiment

According to the first embodiment, when the phase angle θβ is used inthe predicted range, the effect of outputting the two voltage vectorsfor bringing the mode into the power running mode in the power runningoperation state to decrease the power loss, which has not hitherto beenprovided, is provided, but according to a second embodiment of thepresent invention, a description is given of a method of acquiring thesame effect for an arbitrary phase angle θβ. The configuration of thepower conversion device according to this embodiment is basically thesame as that illustrated in FIG. 1.

Possible setting ranges of the voltage vectors outputting the twovoltage vectors for bringing the mode into the power running mode in thepower running operation state for the phase angle θβ are illustrated inFIG. 33. The same effect is provided by shifting the switching angle ofthe combination of the two voltage vectors by an amount of the phaseangle from the case where the phase angle θβ is 0 degrees.

For example, the two voltage vectors only need to be selected for anarbitrary phase angle θβ as illustrated in FIG. 34 and FIG. 35. FIG. 34is a table for showing a case where the combination of the two voltagevectors is switched at the minimum electrical angle. FIG. 35 is a tablefor showing a case where the combination of the two voltage vectors isswitched at the maximum electrical angle. The same effect as that ofthose two cases of outputting the two voltage vectors for bringing themode into the power running mode in the power running operation state todecrease the power loss, which has not hitherto been provided, isacquired by selecting the two voltage vectors included in the possiblesetting ranges.

According to this embodiment, the phase angle θβ is described as thephase angle of the current vector, but the same effect is provided whenthe phase angle θβ is a phase angle in the two-axis coordinate system ofthe detected current (phase angle) acquired by the phase currentcalculation part 8, a phase angle in the two-axis coordinate system ofthe current command when the control command includes the currentcommand, or a phase angle in the two-axis coordinate system of thevoltage command.

For example, when a large d axis current flows (the phase angle islarge), and the voltage vectors remain normal, a region in which thepower running switches to the regeneration occurs, but the detection canbe carried out in the power running mode by the switching inconsideration of the phase angle of the current command.

Third Embodiment

FIG. 36 is a diagram for illustrating an overall configuration of thepower conversion device according to a third embodiment of the presentinvention. The power conversion device according to the third embodimentof the present invention has almost the same overall configuration asthat of FIG. 1, but is different in a point that a switching signalgeneration part 5 a is configured to output the switching signalscorresponding to the two voltage vectors for bringing the mode into theregeneration mode upon the current detection in the regenerationoperation mode.

A description is now given of a difference in the bus current inaccordance with the combination of the two voltage vectors for a casewhere Iu<Iv<0 and Iw>0 are satisfied while the AC rotating machine 1 isin the regeneration operation state.

In this embodiment, as illustrated in FIG. 37, when the two voltagevectors V1 and V2 are generated by setting Qup, Qvp, and Qwp to 1 inthis sequence, the bus current Idc is detected during the generations ofthe voltage vectors. The sum of the three-phase currents is zero, andwhen any one of the three-phase currents has a different value, thecurrent in least one phase thus has a positive value.

The bus current Idc detected at the time point ts1-1(n) is equal to thecurrent Iu flowing through the U phase, the bus current Idc has anegative value, and the mode is in the regeneration mode in which thebus current Idc flows from the AC rotating machine 1 to the DC powersupply 2 or the smoothing capacitor 4.

The bus current Idc detected at the time point ts1-2(n) is equal to thesign-inverted value −Iw flowing through the W phase, the bus current Idchas a positive value, and the mode is in the regeneration mode in whichthe bus current Idc flows from the AC rotating machine 1 to the DC powersupply 2 or the smoothing capacitor 4.

FIG. 38 is a diagram for illustrating a comparative example of when thetwo voltage vectors V5 and V4 are generated by setting Qwp, Qvp, and Qupto 1 in this sequence, and the bus current Idc is detected during thegenerations of the voltage vectors.

The bus current Idc detected at the time point ts1-1(n) is equal to thecurrent Iw flowing through the W phase, the bus current Idc has apositive value, and the mode is in the power running mode in which thebus current Idc flows from the DC power supply 2 or the smoothingcapacitor 4 to the AC rotating machine 1.

The bus current Idc detected at the time point ts1-2(n) is equal to thesign-inverted value −Iu flowing through the U phase, the bus current Idchas a positive value, and the mode is in the power running mode in whichthe bus current Idc flows from the DC power supply 2 or the smoothingcapacitor 4 to the AC rotating machine 1.

A power loss in the smoothing capacitor 4 is acquired by a product ofthe square of the bus current Idc and the equivalent serial resistanceRc. When the voltage vectors are selected as illustrated in FIG. 37, apower loss is generated in portions in the regeneration mode other thanregions in which the voltage vector is V0 or V7. When the voltagevectors are selected as illustrated in FIG. 38, the period of theregeneration mode is increased by a period of the power running mode, apower loss is generated even in the power running mode, and a power lossincreases when the voltage vectors, which bring the mode into the powerrunning mode in the regeneration operation state, are selected.

Thus, according to the third embodiment, the switching signal generationpart 5 a is configured to output the switching signals corresponding tothe two voltage vectors for bringing the mode into the regeneration modeupon the current detection in the regeneration operation mode, therebyproviding an effect of decreasing the power loss, which has not hithertobeen provided.

The method of outputting the switching signals corresponding to the twovoltage vectors for bringing the mode into the regeneration mode uponthe current detection in the regeneration operation mode only needs tobe applied as in the first embodiment and the second embodiment.

In other words, the present invention is not limited to the respectiveembodiments, and the present invention includes all possiblecombinations thereof. For example, the control in the power runningoperation state according to the first embodiment and the control in theregeneration operation state according to the third embodiment may beswitched therebetween in the respective operation states. Further, thecontrol according to the second embodiment may be applied in therespective power running and regeneration operation states. Then, acontrol device for an electric power steering including a powerconversion device having the above described respective functions may beconstructed.

Moreover, according to the respective embodiments, a description isgiven of the example of the device for which the three-phase AC rotatingmachine is provided, but the present invention is not limited to thethree phases, and can be applied to a device provided with an ACrotating machine having a multi-phase winding of four or more phases.

INDUSTRIAL APPLICABILITY

The power conversion device, and the like, according to the presentinvention can be applied to a power conversion device, and the like, invarious fields.

REFERENCE SIGNS LIST

-   1 AC rotating machine, 2 DC power supply, 3 power conversion part,-   4 smoothing capacitor, 5, 5 a switching signal generation part,-   6 voltage command calculation part, 7 current detection part, 7 a    shunt resistor,-   7 b sample-and-hold device, 8 phase current calculation part,-   41 to 44 permanent magnet, 100 position detector, PT power    conversion unit

1.-8. (canceled)
 9. A power conversion device, comprising: an ACrotating machine including a multi-phase winding of three or morephases; a DC power supply part configured to output a DC voltage; avoltage command calculation part configured to calculate a voltagecommand based on a control command from an outside for the AC rotatingmachine; a switching signal generation part configured to output aswitching signal corresponding to at least two voltage vectorscorresponding to the voltage command; a power conversion part configuredto convert the DC voltage from the DC power supply part to an AC voltagebased on the switching signal to supply the AC voltage to the ACrotating machine; a current detection part configured to detect a buscurrent, which is a current flowing between the DC power supply part andthe power conversion part; and a phase current calculation partconfigured to calculate, based on the bus current, a phase currentflowing through the multi-phase winding of the AC rotating machine,wherein: the current detection part is configured to detect the buscurrent at timings at which the two voltage vectors are respectivelyoutput in accordance with the switching signal; and the switching signalgeneration part is configured to output a switching signal correspondingto a voltage vector for supplying a current from the DC power supplypart to the AC rotating machine at a timing at which the bus current isdetected by the current detection part when the AC rotating machine isin a power running operation state.
 10. A power conversion device,comprising: an AC rotating machine including a multi-phase winding ofthree or more phases; a DC power supply part configured to output a DCvoltage; a voltage command calculation part configured to calculate avoltage command based on a control command from an outside for the ACrotating machine; a switching signal generation part configured tooutput a switching signal corresponding to at least two voltage vectorscorresponding to the voltage command; a power conversion part configuredto convert an electromotive force of the AC rotating machine to a DCvoltage based on the switching signal to supply the AC voltage to the ACrotating machine; a current detection part configured to detect a buscurrent, which is a current flowing between the DC power supply part andthe power conversion part; and a phase current calculation partconfigured to calculate, based on the bus current, a phase currentflowing through the multi-phase winding of the AC rotating machine,wherein: the current detection part is configured to detect the buscurrent at timings at which the two voltage vectors are respectivelyoutput in accordance with the switching signal; and the switching signalgeneration part is configured to output a switching signal correspondingto a voltage vector for supplying a current from the AC rotating machineto the DC power supply part at a timing at which the bus current isdetected by the current detection part when the AC rotating machine isin a regeneration operation state.
 11. The power conversion deviceaccording to claim 9, wherein: the power conversion part is configuredto convert the DC voltage from the DC power supply part to an AC voltagebased on the switching signal to supply the AC voltage to the ACrotating machine in the power running operation state, and to convert anelectromotive force of the AC rotating machine into DC power to supplythe DC power to the DC power supply part in a regeneration operationstate; and the switching signal generation part is configured to outputa switching signal corresponding to a voltage vector for supplying acurrent from the AC rotating machine to the DC power supply part at thetiming at which the bus current is detected by the current detectionpart when the AC rotating machine is in the regeneration operationstate, and to output a switching signal corresponding to a voltagevector for supplying a current from the DC power supply part to the ACrotating machine at the timing at which the bus current is detected bythe current detection part when the AC rotating machine is in the powerrunning operation state.
 12. The power conversion device according toclaim 10, wherein: the power conversion part is configured to convertthe DC voltage from the DC power supply part to an AC voltage based onthe switching signal to supply the AC voltage to the AC rotating machinein the power running operation state, and to convert an electromotiveforce of the AC rotating machine into DC power to supply the DC power tothe DC power supply part in a regeneration operation state; and theswitching signal generation part is configured to output a switchingsignal corresponding to a voltage vector for supplying a current fromthe AC rotating machine to the DC power supply part at the timing atwhich the bus current is detected by the current detection part when theAC rotating machine is in the regeneration operation state, and tooutput a switching signal corresponding to a voltage vector forsupplying a current from the DC power supply part to the AC rotatingmachine at the timing at which the bus current is detected by thecurrent detection part when the AC rotating machine is in the powerrunning operation state.
 13. The power conversion device according toclaim 9, wherein the switching signal generation part is configured toselect the voltage vector based on at least one of a phase angle in atwo-axis coordinate system of a current command when the control commandincludes the current command, a phase angle in the two-axis coordinatesystem of the voltage command, and a phase angle in the two-axiscoordinate system of the phase current acquired by the phase currentcalculation part.
 14. The power conversion device according to claim 10,wherein the switching signal generation part is configured to select thevoltage vector based on at least one of a phase angle in a two-axiscoordinate system of a current command when the control command includesthe current command, a phase angle in the two-axis coordinate system ofthe voltage command, and a phase angle in the two-axis coordinate systemof the phase current acquired by the phase current calculation part. 15.The power conversion device according to claim 11, wherein the switchingsignal generation part is configured to select the voltage vector basedon at least one of a phase angle in a two-axis coordinate system of acurrent command when the control command includes the current command, aphase angle in the two-axis coordinate system of the voltage command,and a phase angle in the two-axis coordinate system of the phase currentacquired by the phase current calculation part.
 16. The power conversiondevice according to claim 12, wherein the switching signal generationpart is configured to select the voltage vector based on at least one ofa phase angle in a two-axis coordinate system of a current command whenthe control command includes the current command, a phase angle in thetwo-axis coordinate system of the voltage command, and a phase angle inthe two-axis coordinate system of the phase current acquired by thephase current calculation part.
 17. The power conversion deviceaccording to claim 9, wherein the switching signal generation part isconfigured to select the voltage vector based on at least one of adirection of one of axial direction components in a two-axis coordinatesystem of a current command when the control command includes thecurrent command, a direction of one of axial direction components in thetwo-axis coordinate system of the voltage command, and a direction ofone of axial direction components in the two-axis coordinate system ofthe phase current acquired by the phase current calculation part. 18.The power conversion device according to claim 10, wherein the switchingsignal generation part is configured to select the voltage vector basedon at least one of a direction of one of axial direction components in atwo-axis coordinate system of a current command when the control commandincludes the current command, a direction of one of axial directioncomponents in the two-axis coordinate system of the voltage command, anda direction of one of axial direction components in the two-axiscoordinate system of the phase current acquired by the phase currentcalculation part.
 19. The power conversion device according to claim 11,wherein the switching signal generation part is configured to select thevoltage vector based on at least one of a direction of one of axialdirection components in a two-axis coordinate system of a currentcommand when the control command includes the current command, adirection of one of axial direction components in the two-axiscoordinate system of the voltage command, and a direction of one ofaxial direction components in the two-axis coordinate system of thephase current acquired by the phase current calculation part.
 20. Thepower conversion device according to claim 12, wherein the switchingsignal generation part is configured to select the voltage vector basedon at least one of a direction of one of axial direction components in atwo-axis coordinate system of a current command when the control commandincludes the current command, a direction of one of axial directioncomponents in the two-axis coordinate system of the voltage command, anda direction of one of axial direction components in the two-axiscoordinate system of the phase current acquired by the phase currentcalculation part.
 21. The power conversion device according to claim 9,wherein the current detection part is configured to detect the buscurrent at a timing at which the voltage vector neighbors a voltagecommand vector when an amplitude of the voltage command is more than athreshold.
 22. The power conversion device according to claim 10,wherein the current detection part is configured to detect the buscurrent at a timing at which the voltage vector neighbors a voltagecommand vector when an amplitude of the voltage command is more than athreshold.
 23. A control device for an electric power steering,comprising the power conversion device of claim 9 so that the ACrotating machine generates a torque for assisting a steering torque of asteering system.
 24. A control device for an electric power steering,comprising the power conversion device of claim 10 so that the ACrotating machine generates a torque for assisting a steering torque of asteering system.
 25. A control method for a power conversion device, thecontrol method comprising: calculating, by a voltage command calculationpart, a voltage command based on a control command from an outside foran AC rotating machine including a multi-phase winding of three or morephases; outputting, by a switching signal generation part, a switchingsignal corresponding to at least two voltage vectors corresponding tothe voltage command; converting, by a power conversion part, a DCvoltage from a DC power supply part to an AC voltage based on theswitching signal to supply the AC voltage to the AC rotating machine,and converting an electromotive force of the AC rotating machine into DCpower to supply the DC power to the DC power supply part; detecting, bya current detection part, a bus current, which is a current flowingbetween the DC power supply part and the power conversion part;calculating, by a phase current calculation part, based on the buscurrent, a phase current flowing through the multi-phase winding of theAC rotating machine; detecting, by the current detection part, the buscurrent at timings at which the two voltage vectors are respectivelyoutput in accordance with the switching signal; and outputting, by theswitching signal generation part, at least one of: a switching signalcorresponding to a voltage vector for supplying a current from the DCpower supply part to the AC rotating machine at a timing at which thebus current is detected by the current detection part when the ACrotating machine is in a power running operation state; and a switchingsignal corresponding to a voltage vector for supplying a current fromthe AC rotating machine to the DC power supply part at a timing at whichthe bus current is detected by the current detection part when the ACrotating machine is in a regeneration operation state.